DNA barcodes identify Central Asian Colias butterflies (Lepidoptera,Pieridae)

A majority of the known Colias species (Lepidoptera: Pieridae, Coliadinae) occur in the mountainous regions of Central-Asia, vast areas that are hard to access, rendering the knowledge of many species limited due to the lack of extensive sampling. Two gene regions, the mitochondrial COI ‘barcode’ region and the nuclear ribosomal protein RpS2 gene region were used for exploring the utility of these DNA markers for species identification. A comprehensive sampling of COI barcodes for Central Asian Colias butterflies showed that the barcodes facilitated identification of most of the included species. Phylogenetic reconstruction based on parsimony and Neighbour-Joining recovered most species as monophyletic entities. For the RpS2 gene region species-specific sequences were registered for some of the included Colias spp. Nevertheless, this gene region was not deemed useful as additional molecular ‘barcode’. A parsimony analysis of the combined COI and RpS2 data did not support the current subgeneric classification based on morphological characteristics.     

All together now

Maintenance of genomic stability during eukaryotic cell division relies on the Spindle Assembly Checkpoint (SAC), which has evolved as a surveillance mechanism that monitors kinetochore-microtubule attachment and prevents APC/C-mediated mitotic exit until all chromosomes are properly attached to the mitotic spindle. Reversible protein phosphorylation has long been accredited as a regulatory mechanism of the SAC. Nevertheless, knowledge of how several mitotic kinases act in concert within the signaling pathway to orchestrate SAC function is still emerging. In a recent study, we undertook a comprehensive dissection of the hierarchical framework controlling SAC function in Drosophila cells. We found that Polo lies at the top of the SAC pathway promoting the efficient recruitment of Mps1 to unattached kinetochores. This renders Mps1 fully active to control BubR1 phosphorylation that generates the 3F3/2 phosphoepitope at tensionless kinetochores. We have proposed that Polo is required for SAC function and that the molecular outcome of Mps1-dependent 3F3/2 formation is to promote the association of Cdc20 with BubR1 allowing proper kinetochore recruitment of Cdc20 and efficient assembly of the Mitotic Checkpoint Complex (MCC) required for a sustained SAC response.     

Proteomic Changes during B Cell Maturation: 2D-DIGE Approach

B cells play a pivotal role in adaptive immune system, since they maintain a delicate balance between recognition and clearance of foreign pathogens and tolerance to self. During maturation, B cells progress through a series of developmental stages defined by specific phenotypic surface markers and the rearrangement and expression of immunoglobulin (Ig) genes. To get insight into B cell proteome during the maturation pathway, we studied differential protein expression in eight human cell lines, which cover four distinctive developmental stages; early pre-B, pre-B, plasma cell and immature B cell upon anti-IgM stimulation. Our two-dimensional differential gel electrophoresis (2D-DIGE) and mass spectrometry based proteomic study indicates the involvement of large number of proteins with various functions. Notably, proteins related to cytoskeleton were relatively highly expressed in early pre-B and pre-B cells, whereas plasma cell proteome contained endoplasmic reticulum and Golgi system proteins. Our long time series analysis in anti-IgM stimulated Ramos B cells revealed the dynamic regulation of cytoskeleton organization, gene expression and metabolic pathways, among others. The findings are related to cellular processes in B cells and are discussed in relation to experimental information for the proteins and pathways they are involved in. Representative 2D-DIGE maps of different B cell maturation stages are available online at http://structure.bmc.lu.se/BcellProteome/.     

Apolipoproteins C-I and C-III Inhibit Lipoprotein Lipase Activity by Displacement of the Enzyme from Lipid Droplets

Apolipoproteins (apo) C-I and C-III are known to inhibit lipoprotein lipase (LPL) activity, but the molecular mechanisms for this remain obscure. We present evidence that either apoC-I or apoC-III, when bound to triglyceride-rich lipoproteins, prevent binding of LPL to the lipid/water interface. This results in decreased lipolytic activity of the enzyme. Site-directed mutagenesis revealed that hydrophobic amino acid residues centrally located in the apoC-III molecule are critical for attachment to lipid emulsion particles and consequently inhibition of LPL activity. Triglyceride-rich lipoproteins stabilize LPL and protect the enzyme from inactivating factors such as angiopoietin-like protein 4 (angptl4). The addition of either apoC-I or apoC-III to triglyceride-rich particles severely diminished their protective effect on LPL and rendered the enzyme more susceptible to inactivation by angptl4. These observations were seen using chylomicrons as well as the synthetic lipid emulsion Intralipid. In the presence of the LPL activator protein apoC-II, more of apoC-I or apoC-III was needed for displacement of LPL from the lipid/water interface. In conclusion, we show that apoC-I and apoC-III inhibit lipolysis by displacing LPL from lipid emulsion particles. We also propose a role for these apolipoproteins in the irreversible inactivation of LPL by factors such as angptl4.     

Algal Turbidity Hampers Ornament Perception,but Not Expression,in a Sex‐Role‐Reversed Pipefish

Sexual ornaments are used both in intra‐ and intersexual contexts, and these signals have evolved to function in the particular habitat the animal is adapted to. Habitat characteristics may, however, change rapidly due to anthropogenic effects, sometimes at rates too fast for many organisms to adaptively respond. In aquatic ecosystems, eutrophication is currently changing chemical as well as visual properties of the environment. Algae blooms increase water turbidity, and the reduction of water transparency thus has the potential to alter visual ornaments and their perception. However, results are not congruent. Rather, algae turbidity may decrease, increase, or leave ornaments unaffected. The effect seems to depend on exposure time, condition, population and species. Here, we found that the perception of sexual signals, but not their expression, was hampered by turbidity in the sex‐role‐reversed pipefish Nerophis ophidion. In a laboratory experiment we found that female sexual ornaments (i.e., blue color markings and a skinfold) and fecundity was unaffected by turbidity. Male adaptive mate choice for larger females with large ornament was, however, hampered under turbid conditions, whereas in clear water males choose larger, more ornamented females. Thus, we show that water turbidity had no effect on signal expression but did hamper ornament perception and consequently randomized mate choice.     

Genetic characterization of the Guinea-Bissau family of Mycobacterium tuberculosis complex strains

In a previous study of Mycobacterium tuberculosis complex isolates from Guinea-Bissau in West Africa, we identified a unique group of strains, designated here as the Guinea-Bissau family of strains, which, although genotypically closely related, phenotypically demonstrated a considerable heterogeneity. We conducted here a detailed genotypic analysis of a subset (n = 35) of these isolates. Based on the data obtained, and by comparison of known corresponding genes in mycobacteria outside the M. tuberculosis complex, we propose that the Guinea-Bissau strains belong to a unique branch of the M. tuberculosis complex tree in between classical M. tuberculosis and classical M. bovis. These observations are discussed in their significance in M. tuberculosis complex classification.     

pH6 antigen of Yersinia pestis interacts with plasma lipoproteins and cell membranes

The bacterial pathogen Yersinia pestis expresses a potential adhesin, the pH6 antigen (pH6-Ag), which appears as fimbria-like structures after exposure of the bacteria to low pH. pH6-Ag was previously shown to agglutinate erythrocytes and to bind to certain galactocerebrosides. We demonstrate that purified pH6-Ag selectively binds to apolipoprotein B (apoB)-containing lipoproteins in human plasma, mainly LDL. Binding was not prevented by antibodies to apoB. pH6-Ag interacted also with liposomes and with a lipid emulsion, indicating that the lipid moiety of the lipoprotein was responsible for the interaction. Both apoB-containing lipoproteins and liposomes prevented binding of pH6-Ag to THP-I monocyte-derived macrophages as well as pH6-Ag-mediated agglutination of erythrocytes. Binding of pH6-Ag to macrophages was not dependent on the presence of LDL receptors. Treatment of the cells with Triton X-100 or with methyl-beta-cyclodextrin indicated that the binding of pH6-Ag was partly dependent on lipid rafts. We suggest that interaction of pH6-Ag with apoB-containing lipoproteins could be of importance for the establishment of Y. pestis infections. Binding of lipoproteins to the bacterial surface could prevent recognition of the pathogen by the host defence systems. This might be important for the ability of the pathogen to replicate in the susceptible host.     

1,1'-bis(anilino)-4-,4'-bis(naphtalene)-8,8'-disulfonate acts as an inhibitor of lipoprotein lipase and competes for binding with apolipoprotein CII

Lipoprotein lipase (LPL) is dependent on apolipoprotein CII (apoCII), a component of plasma lipoproteins, for function in vivo. The hydrophobic fluorescent probe 1,1'-bis(anilino)-4,4'-bis(naphthalene)-8,8'-disulfonate (bis-ANS) was found to be a potent inhibitor of LPL. ApoCII prevented the inhibition by bis-ANS, and was also able to restore the activity of inhibited LPL in a competitive manner, but only with triacylglycerols with acyl chains longer than three carbons. Studies of fluorescence and surface plasmon resonance indicated that LPL has an exposed hydrophobic site for binding of bis-ANS. The high affinity interaction was characterized by an equilibrium constant Kd of 0.10-0.26 microm and by a relatively high on rate constant kass = 2.0 x 10(4) m(-1) s(-1) and a slow off-rate with a dissociation rate constant kdiss = 1.2 x 10(-4) s(-1). The high affinity binding of bis-ANS did not influence interaction of LPL with heparin or with lipid/water interfaces and did not dissociate the active LPL dimer into monomers. Analysis of fragments of LPL after photoincorporation of bis-ANS indicated that the high affinity binding site was located in the middle part of the N-terminal folding domain. We propose that bis-ANS binds to an exposed hydrophobic area that is located close to the active site. This area may be the binding site for individual substrate molecules and also for apoCII.     

Lipoprotein lipase from rainbow trout differs in several respects from the enzyme in mammals

Previously we found lipase activity with characteristics similar to lipoprotein lipase (LPL) in tissues from rainbow trout [Biochim. Biophys. Acta 1255 (1995) 205], whereas no equivalent to the related hepatic lipase could be found. An equivalent to apolipoprotein CII was also identified and characterized [Gene 254 (2000) 189]. We present here the full nucleotide sequence for LPL from rainbow trout (Oncorhynchus mykiss) and have investigated some properties of the enzyme. In contrast to what has been found in mammals, LPL mRNA was expressed in livers of adult trout. This indicates that trout LPL carries out functions that hepatic lipase has evolved to take over in mammals. Trout LPL was unstable at 37 degrees C compared with bovine and human LPL. Two sequence differences that may relate to the instability are that trout LPL lacks the disulfide bridge in the C-terminal domain and lacks Pro(258). This residue is conserved in LPL from all mammals and has been shown to be critical for enzyme stability at 37 degrees C. On chromatography on heparin-Sepharose trout and chicken LPL eluted at higher salt concentration than bovine (or other mammalian) LPL. The C-terminal end of LPL has been implied in heparin binding and the higher heparin affinity of the trout and chicken enzymes may be because they have 17 and 15 extra amino acid residues at the C-terminal end, of which three residues are positively charged.     

Tumour necrosis factor-alpha interacts with biglycan and decorin

The interaction of beta-arrestin-1 with the somatostatin receptor type 2A (sst2A) was monitored using both biochemical and confocal imaging approaches. We show that, using transient transfection of either beta-arrestin-1 or its dominant negative Delta-arrestin-1 in CHO cells stably transfected with the sst2A, beta-arrestin-1 is colocalized with the receptor in endosomal vesicles after somatostatin-induced sequestration. However, this interaction leads to a role of beta-arrestin-1 in the desensitization of the sst2A rather than in the internalization process of the receptor-ligand complex.